1. Field of the Invention
The invention relates to the field of photography, and particularly to a photosensitive material processing apparatus.
2. Description of the Prior Art
The processing of photographic film involves a series of steps such as developing, bleaching, fixing, washing, and drying. These steps lend themselves to mechanization by conveying a continuous web of film or cut sheets of film or photographic paper sequentially through a series of stations or tanks, each one containing a different processing liquid appropriate to the process step at that station.
There are various sizes of photographic film processing apparatus, i.e., large photofinishing apparatus and microlabs. A large photofinishing apparatus utilizes tanks that contain approximately 100 liters of each processing solution. A small photofinishing apparatus or microlab utilizes tanks that may contain less than 10 liters of processing solution.
The chemicals contained in the photographic solution: cost money to purchase; change in activity and leach out or season during the photographic process; and after the chemicals are used the chemicals must be disposed of in an environmentally safe manner. Thus, it is important in all sizes of photofinishing apparatus to reduce the volume of processing solution. The prior art utilized various types of replenishing systems that add or subtract specific chemicals to the photographic solution to maintain a consistency of photographic characteristics in the material developed. It is possible to maintain reasonable consistency of photographic characteristics only for a certain period of replenishment. After a photographic solution has been used a given number of times, the solution is discarded and a new photographic solution is added to the tank.
Activity degradation due to instability of the chemistry, or chemical contamination, after the components of the photographic solution are mixed together causes one to discard the photographic solution in smaller volume tanks more frequently than larger volume tanks. Some of the steps in the photographic process utilize photographic solutions that contain chemicals that are unstable, i.e., they have a short process life. Thus, photographic solutions in tanks that contain unstable chemicals are discarded more frequently than photographic solutions in tanks that contain stable chemicals.
Rollers and guides are used in large volume photographic film processing apparatus to change the direction of travel of film and/or paper. A large volume processing apparatus has sufficient space to allow a gradual angular transition as the film or paper turns a corner, i.e. changes direction by 180.degree..
The prior art realized, that if the volume of the various tanks contained within various sizes of photographic processing apparatus were reduced, the same amount of film or photographic paper may be processed, while reducing the volume of photographic solution that was used and subsequently discarded. One of the problems encountered by the prior art in using smaller volume tanks was that the space was limited so that there was not sufficient space available to allow the rollers and guides utilized in the prior art to change the direction of travel of the film and/or paper.
In addition since the space is small in small volume tanks, the film and/or paper has to change direction at a more acute angle (than the angle used in large volume tanks) which makes it likely for the paper and/or film to jam between the walls of the tank and roller during the turning procedure. When the paper and/or film jammed, the processor would stop and time consuming maintenance procedures would have to be instituted. Furthermore, the images on the photosensitive material may be lost and may be nonreplaceable as the photosensitive material did not go through the proper processing sequence. This may cause tremendous customer dissatisfaction.
When the film and/or paper changed direction in a small volume tank, the film and/or paper were confined in a small area and naturally forced against the walls of the tank. The above was caused by: the stiffness of the film and/or paper; the force exerted by the processing solution on the surface of the photosensitive material; the change in frictional characteristics of hydroscopic material such as those found in the film and/or paper; and the surface characteristics of the photosensitive material.
In very confined spaces when guides such as fingers are used to aid in changing the direction of travel of the photosensitive material, pressure sensation marks, i.e., density lines may occur because of the introduction of the fingers and photosensitive material in the confined area.